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<br /> <br />~ <br />w <br />U1 <br />c:o <br /> <br />SOIL GEOMORPHOLOGY, SOIL SALINITY AND VEGETATION: WOODSIDE, UTAH <br /> <br />The Woodside salinity research site consists of approximately 2245 ha (5550 <br />acres) located 19 km (12 miles) south of Woodside and 2lkm (13 miles) north- <br />west of Green River in Emery County, Utah (Figs. 1, 2). The geology of the <br />'.area consists of eroded pediments of the Bookcliffs (Tertiary) overlying the <br />upper CretaCeous Mancos shale. The r'lancos shale dominates the soil survey <br />area although older pediment surfaces are veneered by colluvium from the <br />overlying Mesa Verde group. These colluvial sediments are dominantly sand- <br />stone. The pediment deposits overlying the residual Mancos shale vary in <br />thickness but become shallower with increasing distance from the Bookcliffs. <br />Little structural deformation of the bedrock is evident in the area except for <br />a 9 degree dip to the east or into the Bookc1iffs. The Manco$ shale is a dark <br />carbonaceous, saline, clay deposit of shallow marine origin. Inter- bedded in <br />the formation are siltstone and sandstone layers that are of either shallow <br />marine or terrestrial origin which interfinger in the much more domi- nant <br />shale units. The overlying Mesa Verde sandstone is a ridge forming, thick, <br />massive, jointed deposit laid down in a subaerial environment. <br /> <br />The desert landscape has a sparse vegetative cover, broad pediment surfaces, <br />and dissected shale badlands. The climate of the Woodside site is extreme <br />with intense hot summers and cold winters. Annual precipitation is generally <br />less than 20 n~ (8 inches) most of which falls during the winter in the form <br />of snow. Redistribution of this snow, due to high winds, is frequent and an <br />important factor in distribution of plant communities. Summer thunderstorms <br />periodically cross the area. Frequently, these storms are of very local or <br />isolated nature and do not cover the entire site. Flash floods often fill dry <br />stream beds after these thunderstorms because of the low permeability/high <br />runoff characteristics of the watersheds. Further hydrologic characterization <br />of this site, based upon rainfall simulation studies, is reported elsewhere in <br />thi s report. <br /> <br />The history of the area's land use has been dominated by livestock grazing. <br />West and Ibrahim, (1968) suggest that most of southeastern Utah has been <br />heavily grazed by sheep. Billings (1949) speculated that paucity of herba- <br />ceous vegetation may be due to the affects of past heavy sheep grazing. <br />Stewart, et a1 (1940) reported that unrestricted grazing of the salt desert <br />shrub vegetation in western Utah has almost eliminated the grass component <br />from the respective plant community types. <br /> <br />Results and Conclusions <br /> <br />Soil Resource Investigations: An Order 3 soil survey has been prepared for <br />the survey area by the S011 Conservation Service. A more detailed survey was <br />prepared as part of this study to better characterize soil depths, texture, <br />chemistry, geomorphic position, vegetation, degree of dissection, slope and <br />rock fragment content. (Schafer, 1981). <br /> <br />Three broad geomorphic units were recognized in the area: 1) a low relief <br />shale, pediment and recent alluvial surface in the western third of the stUdy <br />area; ,2) a remnant old pediment surface developed from Mesa Verde sandstone <br /> <br /> <br />12 <br />